This invention relates to an earthquake sensitive shut-off valve or the like, and particularly to protect gas operated systems from damage caused by abnormal increases in gas pressure. Both residential and commercial building and establishments are supplied with gas, either natural gas or liquid petroleum gas. In either supply of gas there is pressure regulation which is subject to failure, as caused by catastrophic circumstances or by mechanical malfunction. Pressure regulators are involved whereby a high pressure source of gas is reduced in pressure to 1/2 lbs. p.s.i. for domestic use, for example. The high pressure source of natural gas is substantially greater than the end use pressure, and would be damaging to domestic as well as commerical appliances and apparatus, if subjected thereto. For instance, liquid petroleum sources of butane and propane are stored at 160 lbs. p.s.i. which is a damaging pressure when exposed to gas operated appliances and such apparatus by failure or malfunction in the supply source. It is therefore a general object of this invention to provide a pressure responsive control that closes off the gas pressure source in the event of a substantial increase in pressure that would be damaging. In practice, this control is combined with an Earthquake Sensitive Shut-Off Valve as disclosed and claimed in U.S. Pat. No. 3,747,616 issued to Hershall E. Lloyd Jul. 24, 1973.
The earthquake sensitive valve involved herein is characterized by a valve element that is manually set for normal open operation, the valve unit involving a leveled body having a saddle upon which the valve element is normally mounted and from which it is displaceable to drop onto a seat in the flow passage through the valve. It is an object of this invention to displace the valve element from the saddle and onto the seat when pressure is suddenly and substantially increased in the supply source of gas. In practice, there is usually a meter means between the pressure regulated gas supply source and the earthquake sensitive valve that protects the building system and gas operated appliances and/or apparatus.
The usual meter means is adapted to accomodate and handle a normal flow of gas at the aforesaid pressure of 1/2 lbs. p.s.i.. However, said meter means will not accomodate or properly handle flow of gas at the aforesaid pressure of 160 lbs. p.s.i., for example. If and when there is a surge of said high pressure gas, then there is a restriction to flow caused by the surge of gas through the meter means in excess of its normal capacity, and consequently a pressure differential occurs between the upstream and downstream sides of the meter means. In lieu of a meter means, a flow restrictor or orifice is employed in the gas supply source to the earthquake sensitive valve, it being an object of this invention to advantageously employ this differential in pressure, as will be described.
The valve element of the valve as it is disclosed herein is a ball that is adapted to be repositioned upon the saddle by a push pin or the like. And, it is an object of this invention to displace the ball by means of a separate pressure actuated push pin. In practice, the pressure actuated push pin is operated by the aforesaid upstream higher pressure when a surge occurs in the gas pressure supply source, as caused by malfunction due to catastrophic circumstances or mechanical failure.